1. Field of the Invention
The present invention relates to a composition for removing polymer residue of a photosensitive etching-resistant layer, and more particularly, to a composition for removing polymer residue of a photosensitive etching-resistant layer, which is highly capable of removing polymer residue and environmentally friendly.
2. Description of Related Art
A semiconductor fabrication process includes a series of processes for forming a metal wire or a contact point, such as a photolithography process, a dry or wet etching process, a plasma ashing process, and so on, which generate organic or metal residue. This residue should be removed before a subsequent process is performed.
Conventionally, the residue has been removed using a composition composed of hydroxylamine, alcohol amines, water, and a corrosion inhibitor at a high temperature of 60 to 85° C. However, since the composition containing amines generates hydroxyl ions during a water cleaning process, isopropyl alcohol (IPA) has been used as an intermediate rinse to prevent corrosion.
Presently, ACT-935 (available from ACT) and EKC-265 (available from DUPONT) are typical products of the composition used to remove the residue. However, these compositions are limited in application due to galvanic corrosion and toxicity.
In recent years, new compositions using fluorine have been introduced along with developments in cleaning apparatuses and reduction in semiconductor linewidth. These compositions may be applied to a dilute hydrofluoric acid (DHF) cleaning process or a buffered oxide etchant (BOE) (or a mixture of HF and NH4F) cleaning process that belongs to a conventional semiconductor fabrication process. In this case, the DHF or BOE cleaning process is carried out using a polar solvent and a corrosion inhibitor at a room temperature of 20 to 30° C. In the DHF or BOE cleaning process using the compositions containing fluorine, although no intermediate rinse need be performed, there is a disadvantage in which an oxide can attack a pattern.
As described above, the conventional compositions for removing residue lead to the frequent occurrence of corrosion of an underlying layer or damage of a metal wire due to a galvanic reaction, thus greatly affecting an electric resistance. Also, due to particles reattached from the compositions to the surface of a wafer, the yield of semiconductor devices decreases. Further, as these compositions contain toxic chemicals, i.e. phenols, such as catechol and pyrogallol used as corrosion inhibitors and amides or amines used as polar solvents of the compositions, they may have bad effects on the human body.
The amides or amines are basically used for a pH controlling solution of which hydrogen ion concentration is held at a constant level in order to stably remove residue caused by a dry etching process. In conventionally used hydroxylamine, alkanolamine (e.g., monoethanolamine) is mixed with water to buffer hydrogen ions. In fluorine, an organic acid is mixed with amines to form an acidic or basic controlling solution. However, amines corrode metals and cannot form environmentally friendly compositions due to the toxicity as described above.
Accordingly, the inventors have made efforts to develop a cleaning agent, which contains environmentally friendly components and can remove residue caused by a semiconductor fabrication process without inflicting damage on an underlying metal layer that is formed on a semiconductor wafer and formed of titanium (Ti), titanium nitride (TiN), tungsten (W), tungsten nitride (WN), aluminum (Al), copper (Cu), tungsten silicide (WSix), or cobalt silicide (CoSix). Thus, the inventors discovered that a composition for removing polymer residue using tetrahydrofurfuryl alcohol (THFA) instead of phenols as a corrosion inhibitor and using diethylene glycol monoethyl ether (EDG) instead of amines as a pH control agent can effectively remove insoluble residue generated during a semiconductor fabrication process, needs no intermediate cleaning process, and also has no toxicity.